Currently, best management practices for farms, orchards and groves require the use of technologies that minimize the generation of dusts and debris. Dust control measures are required in many current regulatory efforts, implemented to reduce dust impacts to workers on-site, and to residents and citizens offsite. Conservation is also a benefit of reductions in dust generation typically associated with harvesting operations in drier climates.
Specifically, in the harvesting of nuts and fruits, these fruits and nuts are first shaken or otherwise removed from the trees, bushes or vines, as required. The modern retrieval of these nuts and fruits from the ground conventionally requires the use of a conveyor pick-up system. To minimize the generation of dust from these pick-up operations, the conveyors are maintained under negative air pressure. One such fan and conveyor system for ground deposited nuts, is shown in U.S. Pat. No. 5,001,893, which employs a large fan to draw dust and debris through a series of open mesh conveyors to clean a bulk of an agricultural product stream retrieved from an orchard floor. Similarly, U.S. Pat. No. 5,373,688, teaches that the fan can be modified and improved, to better direct the exhausted debris away from the harvester apparatus. U.S. Pat. No. 5,421,147 shows additional improvements to the fan and conveyor system, which includes a debris segregating system, for separating light from heavier debris, and for the improved design of the conveyor itself, to better break-up the debris picked-up into the harvester.
These prior harvesting apparatus perform well to clean dust and debris from the fruits and nuts collected. However these devices generate significant amounts of dust or “PM” defined as particulate material. Specifically, particulate material of greatest concern to human health are “PM10,” which are typically defined as respirable particulate material or dusts with an average aerosol diameter” of less than 10 microns, and PM2.5, which are dusts with an average aerosol diameter of less than 2.5 microns. With significant pressures from regulatory governmental agencies to drastically reduce dust generated by harvesting operations and further to conserve top soils, a great need exists for harvesters with lower dust emission rates.